DISPLAY DEVICE, DISPLAY MODULE, ELECTRONIC APPARATUS AND DRIVING METHOD OF THE DISPLAY DEVICE

• US 20060221006A1
• Filed: 03/29/2006
• Published: 10/05/2006
• Est. Priority Date: 03/31/2005
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: UMEZAKI, Atsushi
• Granted Patent: US 7,714,816 B2
• Time in Patent Office: Days
• US Class Current: 345/76
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2320/029 by monitoring one or more pixels in the display panel, e.g. by monitoring a fixed reference pixel
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element
• CPC Class Codes: G09G 3/3291 in which the data driver supplies a variable data voltage for setting the current through, or the voltage across, the light-emitting elements

Abstract

To provide a display device which can apply a voltage at which an operating point becomes a saturation region even when a light-emitting element deteriorates without applying a voltage to a driving TFT and the light-emitting element larger than necessary. A monitor pixel has a monitor pixel power supply line, a first light-emitting element, and a first TFT, while a pixel in the display region has a power supply line, a second TFT as a driving TFT, a signal line which gives a signal to a gate of the second TFT, a third TFT, and a second light-emitting element. A potential of the monitor pixel power supply line and a gate potential of the first TFT of the monitor pixel are sampled to be set as a potential of the power supply line of the pixel and a potential of the signal line of the pixel, respectively.

Claims

1. A display device comprising:

a current source;

a first wiring;

a second wiring;

a first light-emitting element; and

a first transistor,

wherein one of a source and drain of the first transistor is electrically connected to the current source through the first wiring, and

wherein the other of the source and drain of the first transistor and a gate of the first transistor are electrically connected to the second wiring and one electrode of the first light-emitting element.

2. The display device according to claim 1, wherein the first transistor is a normally off transistor.

3. The display device according to claim 1, wherein the display device is incorporated into an electronic apparatus selected from the group consisting of a video camera, a digital still camera, a goggle type display, a navigation system, an audio reproducing device, a personal computer, a game machine, a mobile computer, a mobile phone, a portable game machine, an electronic book, and an image reproducing device.

4. A display device comprising:

a current source;

a first wiring;

a second wiring;

a first light-emitting element; and

a first transistor,

wherein one of a source and drain of the first transistor and a gate of the first transistor are electrically connected to the current source through the first wiring, and

wherein the other of the source and drain of the first transistor is electrically connected to one electrode of the first light-emitting element and the second wiring

5. The display device according to claim 4, wherein the first transistor is a normally off transistor.

6. The display device according to claim 4, wherein the display device is incorporated into an electronic apparatus selected from the group consisting of a video camera, a digital still camera, a goggle type display, a navigation system, an audio reproducing device, a personal computer, a game machine, a mobile computer, a mobile phone, a portable game machine, an electronic book, and an image reproducing device.

7. A display device comprising:

a current source;

a first wiring electrically connected to a first sampling circuit;

a second wiring electrically connected to a second sampling circuit;

a first light-emitting element; and

a first transistor,

wherein one of a source and drain of the first transistor is electrically connected to the current source through the first wiring, and

wherein the other of the source and drain of the first transistor and a gate of the first transistor are electrically connected to the second wiring and one electrode of the first light-emitting element.

8. The display device according to claim 7, wherein the first transistor is a normally off transistor.

9. The display device according to claim 7, wherein the display device is incorporated into an electronic apparatus selected from the group consisting of a video camera, a digital still camera, a goggle type display, a navigation system, an audio reproducing device, a personal computer, a game machine, a mobile computer, a mobile phone, a portable game machine, an electronic book, and an image reproducing device.

10. A display device comprising:

a current source;

a first wiring electrically connected to a digital-analog converter circuit;

a second wiring electrically connected to the digital-analog converter circuit;

a first light-emitting element; and

a first transistor,

wherein one of a source and drain of the first transistor is electrically connected to the current source through the first wiring, and

wherein the other of the source and drain of the first transistor and a gate of the first transistor are electrically connected to the second wiring and one electrode of the first light-emitting element.

11. The display device according to claim 10, wherein the first transistor is a normally off transistor.

12. The display device according to claim 10, wherein the display device is incorporated into an electronic apparatus selected from the group consisting of a video camera, a digital still camera, a goggle type display, a navigation system, an audio reproducing device, a personal computer, a game machine, a mobile computer, a mobile phone, a portable game machine, an electronic book, and an image reproducing device.

13. A display device comprising:

a current source;

a first wiring;

a second wiring;

a third wiring;

a first light-emitting element;

a second light-emitting element;

a first transistor wherein one of a source and drain of the first transistor is electrically connected to the current source through the first wiring, and the other of the source and drain of the first transistor and a gate of the first transistor are electrically connected to the second wiring and one electrode of the first light-emitting element;

a second transistor wherein one of a source and drain of the second transistor is electrically connected to the third wiring, and the other of the source and drain of the second transistor is electrically connected to one electrode of the second light-emitting element;

a first sampling circuit holding a potential of the first wiring for a certain period and supplying the potential to the third wiring;

a second sampling circuit holding a potential of the second wiring for a certain period;

a digital-analog converter circuit wherein a minimum output potential and a maximum output potential are determined by the potential held in the first sampling circuit and the potential held in the second sampling circuit; and

a circuit supplying a signal in accordance with an output of the digital-analog converter circuit to a gate of the second transistor.

14. The display device according to claim 13, wherein the potential of the signal in accordance with the output of the digital-analog converter circuit is smaller than the potential of the first wiring.

15. The display device according to claim 13, wherein the first transistor and the second transistor are P-channel transistors.

16. The display device according to claim 13, wherein a channel width and a channel length of the first transistor are the same as a channel width and a channel length of the second transistor.

17. The display device according to claim 13, wherein the first transistor and the second transistor are formed over the same substrate as the second light-emitting element.

18. The display device according to claim 13, wherein an operating point of the first transistor and the first light-emitting element and an operating point of the second transistor and the second light-emitting element are a saturation region of the first transistor and a saturation region of the second transistor respectively.

19. The display device according to claim 13, wherein a structure of first light-emitting element is the same as a structure of the second light-emitting element.

20. The display device according to claim 13, wherein the first transistor is a normally off transistor.

21. The display device according to claim 13, wherein the display device is incorporated into an electronic apparatus selected from the group consisting of a video camera, a digital still camera, a goggle type display, a navigation system, an audio reproducing device, a personal computer, a game machine, a mobile computer, a mobile phone, a portable game machine, an electronic book, and an image reproducing device.

22. A display device comprising:

a current source;

a first wiring;

a second wiring;

a third wiring;

a fourth wiring;

a fifth wiring;

a first light-emitting element;

a second light-emitting element;

a first transistor wherein one of a source and drain of the first transistor is electrically connected to the current source through the first wiring, and the other of the source and drain of the first transistor and a gate of the first transistor are electrically connected to the second wiring and one electrode of the first light-emitting element;

a second transistor wherein one of a source and drain of the second transistor is electrically connected to the third wiring, and the other of the source and drain of the second transistor is electrically connected to one electrode of the second light-emitting element;

a third transistor wherein one of a source and drain of the third transistor is electrically connected to the fourth wiring, and the other of the source and drain of the third transistor is electrically connected to a gate of the second transistor, and a gate of the third transistor is electrically connected to the fifth wiring;

a first sampling circuit holding a potential of the first wiring for a certain period and supplying the potential to the third wiring;

a second sampling circuit holding a potential of the second wiring for a certain period;

a digital-analog converter circuit wherein a minimum output potential and a maximum output potential are determined by the potential held in the first sampling circuit and the potential held in the second sampling circuit;

a source driver supplying a signal in accordance with an output of the digital-analog converter circuit to the fourth wiring; and

a gate driver supplying a selection signal to the fifth wiring.

23. The display device according to claim 22, wherein the potential of the signal in accordance with the output of the digital-analog converter circuit is smaller than the potential of the first wiring.

24. The display device according to claim 22, wherein the first transistor and the second transistor are P-channel transistors.

25. The display device according to claim 22, wherein a channel width and a channel length of the first transistor are the same as a channel width and a channel length of the second transistor.

26. The display device according to claim 22, wherein the first transistor and the second transistor are formed over the same substrate as the second light-emitting element.

27. The display device according to claim 22, wherein an operating point of the first transistor and the first light-emitting element and an operating point of the second transistor and the second light-emitting element are a saturation region of the first transistor and a saturation region of the second transistor respectively.

28. The display device according to claim 22, wherein a structure of first light-emitting element is the same as a structure of the second light-emitting element.

29. The display device according to claim 22, wherein the first transistor is a normally off transistor.

30. The display device according to claim 22, wherein the display device is incorporated into an electronic apparatus selected from the group consisting of a video camera, a digital still camera, a goggle type display, a navigation system, an audio reproducing device, a personal computer, a game machine, a mobile computer, a mobile phone, a portable game machine, an electronic book, and an image reproducing device.

31. A display device comprising:

a current source;

a first wiring;

a second wiring;

a third wiring;

a first light-emitting element;

a second light-emitting element;

a first transistor;

a second transistor;

a first sampling circuit electrically connected to the first wiring and the third wiring;

a second sampling circuit electrically connected to the second wiring; and

a digital-analog converter circuit electrically connected to the first and second sampling circuits,

wherein one of a source and drain of the first transistor is electrically connected to the current source through the first wiring, and the other of the source and drain of the first transistor and a gate of the first transistor are electrically connected to the second wiring and one electrode of the first light-emitting element, and

wherein one of a source and drain of the second transistor is electrically connected to the third wiring, and the other of the source and drain of the second transistor is electrically connected to one electrode of the second light-emitting element.

32. The display device according to claim 31, wherein the first transistor and the second transistor are P-channel transistors.

33. The display device according to claim 31, wherein a channel width and a channel length of the first transistor are the same as a channel width and a channel length of the second transistor.

34. The display device according to claim 31, wherein the first transistor and the second transistor are formed over the same substrate as the second light-emitting element.

35. The display device according to claim 31, wherein a structure of first light-emitting element is the same as a structure of the second light-emitting element.

36. The display device according to claim 31, wherein the first transistor is a normally off transistor.

37. The display device according to claim 31, wherein the display device is incorporated into an electronic apparatus selected from the group consisting of a video camera, a digital still camera, a goggle type display, a navigation system, an audio reproducing device, a personal computer, a game machine, a mobile computer, a mobile phone, a portable game machine, an electronic book, and an image reproducing device.